Physicists use everyday words in seemingly strange and very specific ways. For a physicist, work W isn't what you do from nine to five on weekdays. It's the product of the force F applied to an object multiplied by the distance d the object moves as a result of that force.
Defining Power in Physics
If the object doesn't move, no work has been done. Try explaining that to the man who is trying to push your car out of a ditch and having no luck getting the car to move. Physicists also use the word power P in a specific way. For them power isn't what you get by eating a hearty breakfast.
It's the time t it takes to do a certain amount of work. In other words, power is the rate of doing work. It's also the rate of transfer of heat and electrical energy. Knowing what the word "power" means to physicists helps you understand the units of power. In the SI metric system, the units are watts. All the other units are derived from these. In the SI system, length is measured in meters, mass in kilograms and time in seconds. The joule is also the unit of energy in the SI system, although it's customary to use ergs when measuring in centimeters and grams.
Scientists have another name for this unit, too. It's the watt, named after James Watt, the Scottish inventor who helped develop the steam engine that powered the Industrial Revolution. In the SI system, the watt is defined as:. If you like cars, you know the power ratings of car engines are always given in horsepower. That means horsepower is also a unit of power, but where did it come from, and why is it still in use? It turns out that none other than James Watt is the man responsible for this unit of power.
In order to sell his steam engines, he had to quantify the amount of work they could do in a certain time. He created a unit based on how much work a single pit pony could do. It was well known at the time that a single pony could lift pounds of coal up a foot mine shaft in one minute.
In SI units, that's As a unit of power, the horsepower is usually reserved for engines and — sometimes — air conditioner cooling capacity. Why do we still use it? Probably for the same reason that people in some countries, including the United States, still use the Imperial system of measurement: habit.
Chris Deziel holds a Bachelor's degree in physics and a Master's degree in Humanities, He has taught science, math and English at the university level, both in his native Canada and in Japan.
He began writing online inoffering information in scientific, cultural and practical topics. His writing covers science, math and home improvement and design, as well as religion and the oriental healing arts. If you're measuring in the centimeters and grams, use this conversion:. About the Author. Photo Credits. Copyright Leaf Group Ltd.The watt symbol: W is a unit of power.
In the International System of Units SI it is defined as a derived unit of 1 joule per second and is used to quantify the rate of energy transfer. When an object's velocity is held constant at one meter per second against a constant opposing force of one newtonthe rate at which work is done is one watt.
In terms of electromagnetismone watt is the rate at which electrical work is performed when a current of one ampere A flows across an electrical potential difference of one volt Vmeaning the watt is equivalent to the volt-ampere the latter unit, however, is used for a different quantity from the real power of an electrical circuit.
Two additional unit conversions for watt can be found using the above equation and Ohm's law. The watt is named after the Scottish inventor James Watt. In Octoberat the International Conference on Electric Units and Standards in London,  so-called "international" definitions were established for practical electrical units.
After the 9th General Conference on Weights and Measures inthe "international" watt was redefined from practical units to absolute units i. Texts written before are likely to be using the "international" watt, which implies caution when comparing numerical values from this period with the post watt.
Technologically important powers that are measured in femtowatts are typically found in references to radio and radar receivers. For example, meaningful FM tuner performance figures for sensitivity, quieting and signal-to-noise require that the RF energy applied to the antenna input be specified.
What Is the Unit of Power?
These input levels are often stated in dBf decibels referenced to 1 femtowatt. This is 0. Technologically important powers that are measured in picowatts are typically used in reference to radio and radar receivers, acoustics and in the science of radio astronomy.
One picowatt is the international standard reference value of sound power when this quantity is expressed as a level in decibels.
Important powers that are measured in nanowatts are also typically used in reference to radio and radar receivers. Important powers that are measured in microwatts are typically stated in medical instrumentation systems such as the EEG and the ECGin a wide variety of scientific and engineering instruments and also in reference to radio and radar receivers. Compact solar cells for devices such as calculators and watches are typically measured in microwatts.
A typical laser pointer outputs about five milliwatts of light power, whereas a typical hearing aid for people uses less than one milliwatt. The kilowatt kW is equal to one thousand 10 3 watts. This unit is typically used to express the output power of engines and the power of electric motors, tools, machines, and heaters. It is also a common unit used to express the electromagnetic power output of broadcast radio and television transmitters.
One kilowatt is approximately equal to 1. A small electric heater with one heating element can use 1. The average electric power consumption of a household in the United States is about one kilowatt.
A surface area of one square meter on Earth receives typically about one kilowatt of sunlight from the sun the solar irradiance on a clear day at mid day, close to the equator.
The megawatt MW is equal to one million 10 6 watts. Many events or machines produce or sustain the conversion of energy on this scale, including large electric motors; large warships such as aircraft carriers, cruisers, and submarines; large server farms or data centers ; and some scientific research equipment, such as supercollidersand the output pulses of very large lasers. A large residential or commercial building may use several megawatts in electric power and heat.
The OED also states that megawatt appeared in a 28 November article in the journal Science This unit is often used for large power plants or power grids. For example, by the end of power shortages in China's Shanxi province were expected to increase to 5—6 GW  and the installed capacity of wind power in Germany was The terawatt TW is equal to one trillion 10 12 watts. The total power used by humans worldwide is commonly measured in terawatts.
The most powerful lasers from the mids to the mids produced power in terawatts, but only for nanosecond time frames. The average lightning strike peaks at 1 terawatt, but these strikes only last for 30 microseconds. One such laser is the Lawrence Livermore's Nova laserwhich achieved a power output of 1. The duration of the pulse was roughly 0.
Based on the average total solar irradiance  of 1. In the electric power industrymegawatt electrical MWe  or MW e  refers by convention to the electric power produced by a generator, while megawatt thermal or thermal megawatt  MWt, MW tor MWth, MW th refers to thermal power produced by the plant.Power is increased if work is done faster or energy is transferred in less time.
If work is done faster, power is higher. If work is done slower, power is smaller. More power is seen when the system is both strong in force and fast in velocity. Power is measured in energy joules divided by time. Power is a scalar quantity, it has no direction. Horsepower is often used to describe the power delivered by a machine.
Horsepower is a unit of power in the British system of measurement. It is the power required to lift pounds by one foot in one second and is about watts. The watt is often seen in relation to light bulbs.
In this power rating, it is the rate at which the bulb converts electrical energy into light and heat. A bulb with a higher wattage will use more electricity per unit of time.
If a bulb has a power rating of 50 watts, it will produce 50 joules per second. In an hour seconds it will producejoules.
When you walk a mile, your motive force is displacing your body, which is measured as the work is done. When you run the same mile, you are doing the same amount of work but in less time. The runner has a higher power rating than the walker, putting out more watts. A car with 80 horsepower can produce faster acceleration than a car with 40 horsepower. In the end, both cars are going 60 miles per hour, but the hp engine can reach that speed faster.
In the race between the tortoise and the hare, the hare had more power and accelerated faster, but the tortoise did the same work and covered the same distance in a much longer time. The tortoise showed less power. When discussing power, people are usually referring to average power, P avg. What is the power at a specific time? When the unit of time approaches zero, calculus is needed to derive an answer, but it is approximated by force times speed.
Share Flipboard Email. Andrew Zimmerman Jones. Math and Physics Expert. Andrew Zimmerman Jones is a science writer, educator, and researcher. He is the co-author of "String Theory for Dummies.In physics, power is the amount of energy transferred or converted per unit time. In the International System of Unitsthe unit of power is the wattequal to one joule per second.
In older works, power is sometimes called activity. The output power of a motor is the product of the torque that the motor generates and the angular velocity of its output shaft. The power involved in moving a ground vehicle is the product of the traction force on the wheels and the velocity of the vehicle.
The power of a jet-propelled vehicle is the product of the engine thrust and the velocity of the vehicle. The rate at which a light bulb converts electrical energy into light and heat is measured in watts — the electrical energy used per unit of time. Power is the rate with respect to time at which work is done; it is the time derivative of work:. In this case, power can be written as:. If instead the force is variable over a three-dimensional curve C, then the work is expressed in terms of the line integral:.
Hence the formula is valid for any general situation. The dimension of power is energy divided by time. Other common and traditional measures are horsepower hpcomparing to the power of a horse; one mechanical horsepower equals about As a simple example, burning one kilogram of coal releases much more energy than does detonating a kilogram of TNT but because the TNT reaction releases energy much more quickly, it delivers far more power than the coal.
It is the average amount of work done or energy converted per unit of time. The average power is often simply called "power" when the context makes it clear. In the case of constant power Pthe amount of work performed during a period of duration t is given by:. In the context of energy conversion, it is more customary to use the symbol E rather than W. Power in mechanical systems is the combination of forces and movement. In particular, power is the product of a force on an object and the object's velocity, or the product of a torque on a shaft and the shaft's angular velocity.
Mechanical power is also described as the time derivative of work. In mechanicsthe work done by a force F on an object that travels along a curve C is given by the line integral :.
If the force F is derivable from a potential conservativethen applying the gradient theorem and remembering that force is the negative of the gradient of the potential energy yields:. If a mechanical system has no losses, then the input power must equal the output power. This provides a simple formula for the mechanical advantage of the system. Let the input power to a device be a force F A acting on a point that moves with velocity v A and the output power be a force F B acts on a point that moves with velocity v B.
If there are no losses in the system, then. These relations are important because they define the maximum performance of a device in terms of velocity ratios determined by its physical dimensions. See for example gear ratios. If the component is a resistor with time-invariant voltage to current ratio, then:. The peak power is simply defined by:. If one defines the energy per pulse as:.
From Wikipedia, the free encyclopedia. Rate at which energy is transferred, used, or transformed. Derivations from other quantities.
Second law of motion.Keep in mind that 50 times the big bet is a fairly common downswing and nothing to become too concerned about if you are still playing to the best of your ability. Trying to just break-even when you are down is a thought that should never enter your mind.
One last suggestion that is extremely important on your trip to becoming a successful poker player is record keeping. This bit of advice is very important. Keeping accurate records is the only way you will be able to make logical and educated decisions for your poker career.
Some players keep very extensive records while others keep none at all. It is recommended keeping track of at least the data contained in the sidebar "Suggested Record of Poker Playing. You will be able to compare your winnings (usually measured in wins per hour) in different games, at different limits, at different times, and at different locations. For example: Solid players usually average 1 to 1. Smart poker players are always looking to improve their performance.
By monitoring your bankroll and your records, you'll improve your chances of walking away from the poker table in the black. The following categories represent the information you need to fully understand your poker playing. Young "Poker Betting Tips" 17 March 2006. Buy-In Some beginning players confuse the terms "bankroll" and "buy-in.
The safest bets come when you know you've got the best hand. Assess your chances by knowing How to Calculate Poker Odds. Of course, sometimes you can win with lousy cards. You can fool them all when you know How to Bluff in Poker. Once you know how to bet, you'll be ready for tougher competition. Go for the brass ring once you've read How to Play Poker in a Tournament. College basketball betting offers sports bettors literally hundreds of games to bet on during a busy Saturday.
With sportsbooks posting spreads and totals on so many games, there are always edges you can find and the best tool for finding those edges is studying accurate college basketball consensus data. Here at Odds Shark (and the various sports sites where we gather NCAA hoops consensus votes and picks), thousands of fans are polled every day, producing college basketball percentages indicating how the public is betting.Bugatti Veyron VS Mercedes AMG F1 Car - Drag Race #6
Use the information to follow the crowd or bet against the public. Bookmark this page for daily NCAA basketball trends to help you enjoy more success at the sportsbook. You pop open a matchup report and see that 81. Remembering your Grade 5 math teacher, you calculate that only 18.
Does this mean you should immediately go bet the Blue Devils because the public clearly knows something that you don't or do you immediately bet on Wake Forest because anytime 81. Casual or recreational bettors (known by the affectionate name of 'squares') often like to bet favorites or bet their favorite teams, regardless of the wagerline.
That means a high percentage isn't always an indicator that the public is right. But your interpretation of the consensus college basketball numbers depends on the way you handicap the games. Regardless, it's critical information and we rate the consensus NCAA basketball picks. We also encourage visitors to make the consensus data even stronger by adding their opinions, predictions, and basketball picks to the equation (by simply clicking on the matchup report links).
Together, all basketball fans can help generate excellent NCAA hoops consensus percentages that will help everyone in the long run. So bookmark this important page and tell your friends.
ST San Jose State PORTL Portland Matchup ARKPB Arkansas-Pine Bluff OREST Oregon State Matchup UT. ST Utah State UTAH Utah Matchup FRSNO Fresno State CALPO Cal Poly Matchup LOYMA Loyola Marymount CSNOR Cal State-Northridge Matchup NARIZ Northern Arizona SD San Diego Matchup ND Notre Dame DELA Delaware Matchup WISGB Wisconsin-Green Bay MIZZU Missouri Matchup PORST Portland State SACLA Santa Clara Matchup TULSA Tulsa KANST Kansas State Matchup HOUST Houston STL Saint Louis Matchup WASST Washington State UTEP UTEP Matchup SUTAH Southern Utah MICHS Michigan State Matchup NEBOM Nebraska-Omaha DRAKE Drake Matchup HOFST Hofstra RIDER Rider Matchup APPST Appalachian State AKRON Akron Matchup WISML Wisconsin-Milwaukee W.My upset of the year: Cleveland gets a win.
As everyone waits for Aaron Rodgers to return, the Packers stumble on the road one week after an overtime game. Houston doesn't have many more opportunities for wins. This is one of them against a team in the midst of a back-to-back on the road. Expect a close one. I'm refusing to totally jump ship on the Chiefs.
Andy Reid is too good of a coach to let this season slip away. Alex Smith and Co. The Lions aren't good enough, but they'll give fans some hope with a win over a poor Bucs team that likely will be looking for a new coach soon. I keep waiting for the other shoe to drop with a Titans team that looks far worse than its record.
A proud Cardinals team can be the group to knock them off. QB power rankingsNew York Jets (-1) at Denver BroncosImagine telling someone before the season that the Jets would be road favorites in Week 14.
It's with good reason. If logic wins out, the Chargers will win the AFC West, host a playoff game and walk into Pittsburgh or New England in the Divisional Round as a dangerous team. Logic rarely wins out with the Chargers. Philadelphia Eagles at Los Angeles Rams (-2)Get your popcorn ready for this one. Two of the best teams in the NFC.
The two top quarterbacks (and overall players) selected in the 2016 NFL Draft. Coach of the Year candidates. Los Angeles' great special teams unit will make a big play, but Carson Wentz will bounce back to lead a game-winning drive. It's impossible to feel confident in taking Blake Bortles in a game he's laying points to Russell Wilson. Earlier this season, Pittsburgh blew the doors off Baltimore.
The Ravens bring a big-time defense to this one and will keep it close. It's amazing how many bad prime time games Miami has been in this year. Get ready for another. All rights reserved (About Us).
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of New Jersey On-Line LLC. Community Rules apply to all content you upload or otherwise submit to this site. Your weather is set to. You can change the location at any time. Consider this a one-stop shop guide to picking every (or at least the majority) game correctly.
New Orleans Saints (-1) at Atlanta Falcons Thursday, Dec. EST If the Falcons want to make the playoffs, this feels like a must win. Indianapolis Colts at Buffalo Bills (PK) Sunday, Dec. EST We could be on the path to Jacoby Brissett vs.
EST This is a big one--and a potential playoff matchup in January.Both are free and easy to integrate into your store. To counter reply to a negative review for example. Can you reply to a review in Bigcommerce. I searched for a way, but no luck. Should I use another service for that feature.
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Take a tip from Neil and be willing to exchange your services for a raving review.